Friday, 11 July 2008

Package Managers As Achilles Heel: "Re:Sounds real and exploitable.. (Score:5, Insightful)by jmorris42 (1458) * on Thursday July 10, @08:22PM (#24145841) Homepage> One long term solution would be to sign package metadata and serve> it only from one central location, over https/sftp.

Even that won't help. The authors got so caught up in the complex exploiting they didn't notice the BIG implication of their work. The problem can't be fixed with tech, crypto or anything but https connects to known to be trusted mirror operators.

Follow along as I demonstrate. Spamgang wants zombies so they install a massive mirror farm for all of the major distros. They run it perfectly, fully updated with upstream as fast as their phat pipe can get it, perfectly signed metadata, packages and everything offered by http or https. Then they wait.

Sooner or later another remote root bug, in openssh for example, will hit and they are ready. Thousands of machines either automatically connect or their owners see the story here on /. and hit the update button. They download that signed, correct metadata and sure enough their machines realize they need that new openssh package and ask the mirror for it. And are 0wned a few milliseconds later.

Because in the act of requesting the package all those machines just told the spamgang that a specific IP is a) running openssh, b) it is the vulnerable version and c) that host is currently connected to the network and very likely has the vulnerable software running. So in the time it takes the updated package to transfer, unpack and install they have ample time to get in and install a rootkit. The beauty is that the victim will patch the hole and thus prevent anyone else from getting the zombie.

Wait a random time before beginning to use the new zombies to help prevent people from getting wise to what is happening and the spamgang could likely get away with it for years."